The following terms are used in the ensuing description, and are defined as follows:                GSM Global System for Mobile Communications, a digital wireless communication system using a Time Division Multiple Access (TDMA) air interface.        GPRS General Packet Radio Service, a GSM phase 2+ service in which radio resources for data transfer are allocated on a per block basis, as opposed to a circuit-switched basis.        MS Mobile Station, such as a handheld cellular telephone, a vehicle-installed cellular telephone, a personal communication device, a personal data assistant (PDA) device having wireless communication capabilities, a wireless communication module installable within or with a computer, such wireless communication module installable within or with a computer, such as by plugging into a PCMCIA slot and, in general, any device capable of bidirectional communication with a wireless network.        DL Downlink: a direction from the wireless network to the MS.        UL Uplink: a direction from the MS to the wireless network.        PSI Packet System Information (message).        PBCCH Packet Broadcast Control Channel: a downlink channel used to broadcast PSI messages.        PACCH Packet Associated Control Channel: a logical channel that is used to send control blocks between the network and the MS on the same channel that packet data blocks are sent (i.e., during packet data transfer)        TBF Temporary Block Flow: a temporary flow of packet data from the MS to the network (UL TBF) or from the network to the MS (DL TBF). If the direction is not specified, TBF means UL TBF, DL TBF, or both.        PTM Packet Transfer Mode: a mode wherein the MS is receiving packet data, sending packet data, or both, that is, the MS has UL TBF, DL TBF, or both UL and DL TBFs active.        Multi-RAT Multi-Radio Access Technology: a MS having both 2G (GSM) and 3G (UMTS) capabilities, e.g., 2G-3G multimode phone that can obtain service in either a 2G or a 3G network.        
During the initial acquisition of PSI messages, for example after cell (re)selection, the network does not necessarily know which PSI messages it needs to send to the MS. This problem will become more prominent in future releases (e.g., those coming after Release 1997 (R97), Release 1998 (R98 and Release 1999 (R99)), as new PSI messages will be introduced. As presently specified, a given MS is not able to inform the network as to which PSI messages it expects to receive from the network.
More specifically, during an Unspecified Update procedure the MS is required to receive at least one instance of each PSI message type. Currently, the Packet PSI Status message is not specified so as to indicate which PSI message type(s) the MS requires in order to perform change mark checking. As such, the currently specified Packet PSI Status procedure cannot be used during a partial acquisition procedure.